This invention is in the field of industrial water systems. Specifically, this invention is in the field of locating hidden microorganism contaminated surfaces in industrial water systems.
Throughout the world, there are many different types of industrial water systems. In the vast majority of these industrial water systems, growth of microorganisms is a problem. Microorganisms can grow in extremely diverse environmental conditions. Although many microorganisms grow at moderate temperatures from about 30xc2x0 C. to about 50xc2x0 C., there are other microorganisms known as phychrophiles that grow at temperatures from about 0xc2x0 C. to about 30xc2x0 C. and thermophiles that grow at temperatures from about 50xc2x0 C. to greater than 90xc2x0 C. In addition to this broad temperature range that permits microbial growth, microorganisms grow over a wide range of pH, osmotic pressure, nutrient concentration and oxygen concentration conditions. Given this wide range of conditions that permit growth, it is not surprising that microorganisms can exist and cause problems in the optimum operation of most industrial water systems.
Sources of microbial contamination in industrial water systems are numerous and may include, but are not limited to, air-borne contamination, water make-up, process leaks and improperly cleaned equipment. These microorganisms can establish microbial communities on any wettable or semi-wettable surface of the water system. Exopolymeric substance secreted from the microorganisms aid in the formation of biofilms as the microbial communities develop on the surface. These biofilms are complex ecosystems that establish a means for concentrating nutrients and offer protection for growth, and biofilms can accelerate scale, corrosion, and other undesirable fouling processes. Not only do biofilms contribute to reduction of system efficiencies, but they also provide an excellent environment for microbial proliferation that can include legionellae bacteria. It is therefore important that biofilms and other fouling processes be reduced to the greatest extent possible to minimize the health-related risk associated with legionellae and other water-borne pathogens.
Many different methods of cleaning biofilms from equipment and piping in industrial water systems are known. One such method, is a method of simultaneously cleaning and disinfecting an industrial water system as described and claimed in U.S. patent application Ser. No. 10/135,317 now pending. U.S. patent application Ser. No. 10/135,317 is incorporated by reference in its entirety.
In order to be most effective, all methods of cleaning biofilms require a modicum of knowledge as to where the biofilm is present. Understanding where a biofilm is present is simplified when it is possible to visibly inspect the surfaces of equipment and piping.
A common practice for the examination of heat exchangers is to use fiber optic probes with small cameras to visualize in realtime and on tape the condition of tube surfaces. Frequently scale, corrosion and microbial fouling can be detected or suspected using this type of sensing device. The fiber optic cables can be many meters long and easily extend the full length of the heat exchanger tubes. The flexibility of the cables also allows them to bend around right angle turns in pipes. By twisting the cable the camera viewing angle can be positioned a full 360 degrees. However, this technique has limitations such as the fact that it only provides visual information which can often be misleading as to the exact nature of the film or deposit. With this method it is possible to mistake water films for microbial deposits. In fact, scale and corrosion deposits are usually more clearly identified visually compared to microbial deposits.
In industrial water systems where it is not possible to visibly inspect the surfaces of equipment and piping, it is customary to provide an excess of treatment chemicals and cleaning chemicals to ensure that all biofilms are cleaned. When the surfaces of equipment and piping are not contaminated with hidden biofilm, the use of an excess of treatment chemicals and cleaning chemicals means a waste of chemicals and thus a waste of money. Therefore, it would be desirable to have a method of identifying where hidden microbiological contamination is present, so as to not have to provide an excess of treatment chemicals and cleaning chemicals when it was not necessary.
The instant claimed invention is a method for locating hidden microorganism-contaminated-surfaces in industrial water systems comprising the steps of:
a) providing an industrial water system;
b) draining the water from said industrial water system or from a targeted portion of said industrial water system;
c) applying a solution or dispersion of a fluorogenic reagent in water to the hidden water contact surfaces of said industrial water system and allowing said fluorogenic reagent to react with any hidden microorganisms present, wherein said fluorogenic reagent is selected from the group of fluorogenic reagents that are known to react with microorganisms such that a fluorescent signal of said fluorogenic reagent is detectable in such a way as to make the detection of the fluorescent signal indicate that there are hidden microorganisms present on the water contact surfaces or water condensable surfaces of the equipment and piping;
d) collecting said solution or dispersion after it has been in contact with the hidden water contact surfaces of said industrial water system;
e) providing means for measurement of the fluorescent signals of said fluorogenic reagent in the collected solution or dispersion;
f) using said means for measurement of said fluorescent signals of said fluorogenic reagent to measure the fluorescent signal of the fluorogenic reagent; and
g) using the measured fluorescent signal to determine whether hidden microorganisms are present on the water contact surfaces of the equipment and piping of the industrial water system.